[analyzer] Detect ObjC properties that are both (copy) and Mutable.

When an Objective-C property has a (copy) attribute, the default setter
for this property performs a -copy on the object assigned.

Calling -copy on a mutable NS object such as NSMutableString etc.
produces an immutable object, NSString in our example.
Hence the getter becomes type-incorrect.


Differential Revision: https://reviews.llvm.org/D27535

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@289554 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit bcb98cc24406e72080d913a0e4f4e089da1aa5dd)
4 files changed